This talk will review how one can use interference experiments to study non-trivial properties of low dimensional fluctuating condensates. I will show that the suppression of interference fringes in experiments with independent condensates contains information about correlation functions including the high order ones. Quantitative analysis of the fringe amplitude suppression can reveal the Luttinger liquid behavior of one-dimensional condensates and the Kosterlitz-Thouless transition in two-dimensional systems. Connection of these experiments to other problems in condensed matter physics and field theory will be discussed. I will also demonstrate that the study of non-equilibrium dynamics in a system of coupled one-dimensional condensates can be used to investigate the rich spectrum of the quantum sine-Gordon model.